86%

of those 15,000,000,000,000 watt-hours

come from carbon-based fuels

(coal, petroleum, natural gas);

that produce carbon dioxide when burned.

Only 14% is NOT carbon-based.

But our use of carbon fuels has hidden costs.

and serious consequences.

 

1. What are these consequences and why are they so serious?
2. 15,000,000,000,000 sounds big. How much is it?
3. Why are coal, oil, and natural gas called carbon-based?
4. What is carbon dioxide? Where does it come from?